Syrian forces encircling the city of Homs have issued a 72-hour ultimatum for all protests against President Bashar al-Assad to stop, or a new offensive will begin.

Members of the Free Syrian Army, a rebel movement with a strong presence in HomsPhoto: CORBIS

By Ruth Sherlock in Beirut

9:00PM GMT 09 Dec 2011

The warning came as the regime's troops massed outside the city, apparently preparing for a major operation. Homs has been a centre of unrest since the onset of demonstrations against Mr Assad in March. The biggest protests have traditionally taken place on Fridays, the day of prayer in the Muslim world, when the mosques fill with worshippers.

On Friday, the security forces tried to curb the unrest by issuing an explicit threat. "We have been given 72 hours to stop protesting, or they are going to hit us hard," said an opposition activist in Homs going by the name Abu Rami.

Nonetheless, demonstrations swept across the city after prayers. People left the mosques and filled the streets, chanting "Syria wants freedom" and "Bashar is an enemy of humanity".

Witnesses said the security forces responded with violence, firing live rounds at some crowds. By last night, the Syrian Observatory for Human Rights, a London-based group, estimated that up to ten people had been killed in Homs.

Abu Rami said the security forces were "going mad in Homs", adding: "They are shooting everything, especially at people going outside from the mosques."

More fighting broke out between the Free Syrian Army, a rebel movement with a strong presence in Homs, and the regime's forces. An opposition activist reported "heavy gunfire and explosions" in the neighbourhood of Karm as-Zeitoun, adding: "Our fighters are trying to protect the protesters." The Syrian National Council, an alliance of opposition parties, claimed in a statement that the forces outside Homs were preparing a "massacre".

They have resorted to new and increasingly violent tactics to deter civilians from joining the street protests, according to witnesses. A network of checkpoints has been established across Homs to pen in the demonstrators. At one roundabout, armoured vehicles had "made a checkpoint and are shooting randomly," said an activist calling himself Waleed.

Video footage showed the corpse of an eight-year-old boy, Mahar al-Huseini, lying on a couch in his home, blood pouring from a bullet wound to the head. He had been playing inside the house when a bullet entered through the window.

"He was alive for half an hour, but we can't take him to the hospital. It is too dangerous to leave the home," said one of the boy's relatives.

The regime has tried to seal off the districts of Homs most affected by protests, severing electricity supplies and communications. Some areas have been surrounded by newly dug trenches. "The trenches are huge. It makes it difficult for us to get in an out without going past army checkpoints, or to take the injured to the hospital," added Waleed.

Some protests also took place in the suburbs of the capital, Damascus, according to activists. In the suburb of Kfr Batna, security forces are reported to have opened fire on civilians.

As the unrest continued, Turkey warned that it would not "stand by" if Syria's violence threatened its own security. "Turkey has no desire to interfere in anyone's internal affairs, but if a risk to regional security arises then we do not have the luxury of standing by and looking on," said Ahmet Davutoglu, the Turkish foreign minister.

"If a government that is fighting its own people and creating refugees, is putting not only their own security at risk, but also that of Turkey, then we have a responsibility and the authority to say to them: 'Enough'!"

But splits have emerged within the movement opposing Mr Assad. Burhan Ghalioun, leader of the Syrian National Council, urged the Free Syrian Army to restrain its operations. "We are worried that we will slide towards a civil war which pits a free army and an official army against each other," he told Reuters. "We want to avoid a civil war at all costs."

The Free Syrian Army should confine itself to protecting civilians, added Mr Ghalioun, and refrain from attacking the regime's security forces. He urged Riyad al-Asad, the leader of the rebel force, to show restraint. "It is fundamental for the success of our revolution to preserve its peaceful character," said Mr Ghalioun. "That means popular demonstrations."